Footage emerged of an incident, prior to the match, which saw the man pushed back onto the platform while he tried to board the train, with supporters also heard chanting "We're racist, and that's the way we like it".

The Conservative leader declared: "It's obviously potentially a criminal offence and so I'm sure the French police will be looking at it very seriously," he told LBC radio.

"I know the British police will give every assistance that they can. I'm sure Chelsea will co-operate with that fully. These are very, very serious matters."

Prosecutors in Paris have stated that any Chelsea fans found guilty of of racial abuse face a possible three-year jail sentence and €45,000 (£33,160) fine.

Chelsea have also condemned the actions of those involved through a statement published hours after the incident took place, saying it will issue bans to any of its fans found to have been involved.

The chairman of the Chelsea Supporters' Trust has also condemned the incident.

Tim Rolls, who was in Paris but did not see the incident, said that the actions of some fans' were "depressing", however declared that the attitudes and views displayed did not represent the 2,000 fans who went to France.

“We, the supporters’ trust, condemn the chanting and we support what the club have said about it. It is half a dozen people.